Cards which have a strip of magnetic material on them on which information can be encoded magnetically by a card reading and writing head are very well known. They are widely used in electronic banking and to control entry to and exit from public transport systems. In circumstances such as these, however, the card writer is generally a relatively complex piece of machinery and is generally very expensive. Also it is usually housed indoors so that it is well protected from the environment. Further, this usually uses a plentiful supply of electricity to drive some form of electric motor which advances the card past the read-write head at a substantially constant speed so that consistent writing can be achieved.
It would be very desirable to adapt this type of technology to simple situations like parking meters. Thus, a user could get a stored value ticket from a central location and then insert that into a parking meter where he parks his car and the parking meter would then automatically check the ticket, extract the appropriate time by reading the remaining time on the stored value ticket and re-writing with the reduced remaining value. Parking meters, however, do not have a ready supply of electricity for driving a motor and also it would not be practical to use a very expensive card writer in such circumstances because of the numerous parking meters which exist.
It is therefore an object of the invention to provide a system which is much simpler and whereby the user can manually insert and withdraw the ticket so that only a relatively small power supply, e.g. as obtainable from a battery pack, is necessary to drive the electronics associated with the read-write head.